[Blood pressure and hormonal regulation in active and passive orthostasis]

The procedure using a tilt-table is far better standardized and less dependent on the patient's compliance compared to the active manoeuvre of standing up. The object of this study is to detect to what extent results are comparable concerning hormonal regulation and the adaptation of blood pressure. In 20 males (59.1 +/- 10.9 years), without any evidence of central nervous disorder, we measured the systolic, diastolic and the median blood pressure, heart frequency and hormone levels (noradrenaline, aldosterone, renin) at rest and over 10 minutes in the upright position after actively or passively (by tilt-table) assuming an orthostatic posture. The blood pressure showed little change after the patient sat upright himself, whereas the passive manoeuvre caused a significant decline of systolic blood pressure lasting over the entire sampling period. The adaptation of hormone levels and heart frequencies, however, showed no significant differences. Renin and aldosterone rose in both examinations. Noradrenaline showed an increase of 100% after active assumption of orthostatic posture and 80% using the tilt-table. Hence in patients who are passively brought into the upright position there is no increased noradrenaline output to stabilize blood pressure. This points to the fact that orthostatic circulatory mechanisms are not sufficiently brought into play after the non-physiological passive manoeuvre.

(1.) the tilt-table compared to active orthostatic posture provides better standardized conditions; (2.) there are no significant differences in hormone levels; and (3.) maneuvering patients into an upright position provides a greater risk of fainting due to a pathological fall in blood pressure.